PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 299 



ROADS AND MAII, ROUTES. 



Among' tlic early wants of the settler were means of intercommunieation 

 Although to facilitate their meetings Indian trails were widened into wagon 

 ways, and swamps were made passable by means of log foundations, com- 

 motdy called corduroy roads, the services of the Civil Engineer were soon 

 reijuired to lay out highways anVl construct bridg(!s. Subsequently, turn- 

 pike companies were chartered in every State. Permanent roads, having 

 a stone substructure reachiug below the point affected by frost, were first 

 commenced by the General Government, upon the admission of the State 

 of Ohio in the Union. The Great National road leading from both Wash- 

 ington and Baltimore westward is more than 600 miles in extent, and cost 

 $3,500,000. The amount expended by the (jOTcrnment in public improve- 

 ments up to the time of General Jackson's Administration was ,S30, 000,000. 

 Til most cases the work was accomplished under the direction of the War 

 Department, the roads in the new States being constructed by the army. 



Owing to improvements in locomotion, which will be noticed presently, 

 the means of intercommunication by mail have been inci:eased beyond pre- 

 cedent. In 1791, there were in the United States but 89 postofBces; in 

 18G0, the number exceeded 28,000. During this interval post roads were 

 extended more than 258,000 miles. The total distance over which mails 

 were transported during the last mentioned year exceeded 258 millions of 

 miles. 



MOTORS. 



In reverting to the histor}^ of the early settlement of the Eastern States, 

 it will be found that a vast amount of work was accomplished by the 

 use of water power, derived from the numerous rapid streams. The con- 

 structing of dams and water courses, the erecting of mills, and the improve- 

 ment of water-wheels, required the exercise of more than ordinary skill and 

 ingenuity. Disastrous consequences not nnfrequently Ibllowed a want of 

 knowledge of the laws of hydrodynamics. Tlie sawmill greatly expedited 

 the conversion of forests into materials for immediate use; and after the 

 invention of an American machine which could cut, from a wrought-iron 

 plate, a nail, and head it at one operation, hj which nails were supplied in 

 abundance, buildings of all kinds were erected with great rapidity and at 

 comparativel}' small expense. 



The next important use to which water-power was applied, was in the 

 grinding of grain. By the ingenious improvements of Oliver Evans, invented 

 about the close of the Revolution, the flourmill was made automatic; thus 

 dispensing with the labor of every man except one in the ordinary Grist- 

 mill. The saving effected by this single invention in this country during 

 the last fifty years, will be admitted to be immense, when we take into 

 consideration the statement in the last census report, that the value of the 

 product of flour and grist mills for the year 1860 exceeded 223 millions of 

 dollars. 



The world is indebted to the genius of tlic same Oliver Evans for the 

 plan of using the direct pressure of steam as a motor; steam having been" 

 previously used in the Scotch Enp-ine to produce a vacuum beneath a pis- 

 ton, in order to render effective the pressure of the atmosphere above it. 

 The High Pressure Steam Engine was invented by Evans in 1780, but was 



